The present inventions relate to monitoring, display and control systems for use in water and wastewater treatment. More particularly, the present inventions relate to the manipulation, transformation and display of oxidation-reduction potential data in intermittently aerated, batch wastewater treatment processes leading to meaningful process interpretation, as well as the control and optimization of such processes.
There are a variety of known systems which monitor and control the biological treatment of water and wastewater. Supervisory control and data acquisition (SCADA) systems, tailored to the needs of the water and wastewater treatment industry are typical. SCADA systems usually include sensors in a tank or basin, remote terminal units (RTU's) or programmable logic controllers (PLC's) that convert the signals from the sensors to digital data that is transferred to supervisory computers (PC's) which gather and process the data. The PC may be used to control a particular operation, such as the addition of chemicals and the duration of process phases. A display or monitor, typically associated with the PC, is also provided so that an operator may view and interpret the data and interact with the system. These systems may be active (i.e., they are used to directly control the process based upon data and without operator input) or passive (i.e., they inform the operator of process conditions and the operator acts on that information).
One system specifically designed for the needs of the water and wastewater treatment industry is the IntelliPro® process management and control system of Aqua-Aerobic Systems, Inc., Rockford, Ill. Unlike the SCADA systems typically used for control of an entire plant, the IntelliPro® system is specifically designed for more focused and specialized control of treatment plant subsystems, such as secondary biological processes, but may be used in conjunction with SCADA systems for overall plant, process or subsystem control. For example, the IntelliPro® system is particularly useful for control and monitoring of sequencing batch reactor (SBR) processes, as well as other secondary biological processes, such as membrane filtration and activated sludge systems.
Water condition parameters monitored in typical SBR control systems include dissolved oxygen (DO), pH, temperature, nitrates, phosphates, ammonia and the like. Oxidation Reduction Potential (ORP) has also been monitored and raw data displayed, typically as a plotted curve of ORP values over many cycles of operation (see FIG. 2). However, because of the nature and display of ORP readings, plant operators and others typically have not been able to use ORP data to meaningfully interpret and control process parameters, particularly in real time or substantially real time. This is because, for example, the value of an ORP reading of the reactor contents at any given point in time during a process does not necessarily equate to the particular state of a biological treatment process. In fact, it has been determined as part of the present inventions that only a comparison of the information including the slope of the plotted ORP curve (i.e., ORP value plotted over time), and changes thereto, provides meaningful state information, as discussed herein. Until the present inventions, meaningful ORP information, particularly in essentially real time, and the ability to determine and control treatment process operations based upon such readings, actively or passively, was unavailable.
Thus, when properly processed, manipulated and displayed as discussed herein, ORP can be a more reliable indicator of process condition or state of the reactor contents than many indicators currently used, such as dissolved oxygen. In particular and especially when used in conjunction with an SBR, the present inventions accurately determine the state of the contents in the SBR reactor, i.e., anaerobic, anoxic and/or aerobic (oxic), that can be used alone or with other data or water condition parameters for active or passive control and optimization of the treatment process. In addition, the present inventions overcome the problems and shortfalls associated with the use of ORP level readings from biological treatment processes, and provide a unique way to calculate, display and control wastewater treatment systems using ORP data, including the use of available spreadsheet software.